The usefulness of p16^INK4a immunocytochemical staining in ASC-H patients

Background: The grey zone of cervical cytology, and in particular atypical squamous cells, cannot exclude HSIL (ASC-H) causes diagnostic difficulties and increases medical expenses. We analyzed p16INK4a expression in ASC-H liquid-based cytology specimens (LBCS) to develop more effective methods for the management of ASC-H patients. Methods: We carried out p16INK4a immunostaining with 57 LBCS of ASC-H diagnostic categories, all of which were histologically cofirmed and 43 cases of which were compared with the results of a human papillomavirus (HPV) chip test. Results: p16^INK4a immunostaining with ASC-H LBCS was positive in 20% (3/15) of cervicitis, 25.0% (3/12) of tissue-low-grade squamous intraepithelial lesion, 75.0% (18/24) of tissue-high grade squamous intraepithelial lesion (HSIL), and 100% (6/6) of invasive cancer cases. The positivity of p16^INK4a in LBCS was correlated with higher grade of histologic diagnosis (r=0.578, p=0.000). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of p16^INK4a immunostaining for the prediction of tissue-HSIL+ were 80.0%, 77.8%, 80.0%, and 77.8%, respectively. The sensitivity, specificity, PPV, and NPV of p16^INK4a immunostaining plus HPV chip test for predicting tissue-HSIL+ were 71.2%, 86.4%, 84.2%, and 79.2%. Conclusions: p16^INK4a immunostaining as well as HPV chip testing with remaining LBCS with ASC-H are useful objective markers for the prediction of tissue-HSIL+.